Fineness of the Cement is tested to calculate how fine cement is. It helps to determine how fine and coarse particles are available in Cement. Fineness of the cement is directly Proportional to the hydration rate of the cement. More fine cement means fast rate of hydration. Fine Cement offers higher surface area. Higher surface area leads to Faster hydration and faster gaining of the strength. Faster rate of strengthening may leads to cracks in concrete or shrinkage in it. So Finding accurate fineness in concrete is important.
Apparatus and Material Requirement: –
- Cement: – Take Sufficient Sample of Cement which are about to test. We must take 3 tests to find average of the test results. So if one test have 100 grams of Cement then it means requirement of the cement is 300 grams.
- Weigh Scale: – Weight scale is important to calculate accurate weight of the sample cement and resulted cement. Least count of the scale must be 10 mg.
- Sieve: – A Stainless steel sieve of 90 Micron cloth is used. Its Diameter should be around 150 mm to 200 mm and Depth should be around 40 mm to 100 mm. Sieve must Cylindrical, non Corrodible, Durable and clean.
- Brush: – It is used for cleaning purposes.
Procedure: –
- Take Sample of cement. Weight of the sample should be around 3000 grams. One test would be of 1000 gram sample. We are repeating the test 3 times for accuracy.
- Make sure there are no existing lumps in the cement.
- Take 1st 1000 Gram (W1) cement sample and pour it in 90 micron sieve and close the lead.
- Shake Sieve for 15 minutes. Shaking machine can be used. If shacking machine is not available then shake it manually for 15 minutes.
- Now check the weight of the cement which is retained on the sieve (W2).
- Now calculate the % of cement retained on the sieve.
- percent of the Cement Retained on the sieve= (W2/W1) x 100
- Repeat this test 3 times to get accurate results.
Results: –
Good fineness of the cement is when cement retained on the 90 Micron Sieve should not exceed 10%
Example: –
In this case Average Fineness is 8.58%. Means is cement is passed.
